Elimination of nucleation sites in pressure chamber for ink jet systems

Abstract

In the particular embodiments of the invention described in the specification, the pressure chamber for an ink jet system is coated with a smooth, conforming layer of a coating material, such as a xylylene polymer material, which is wettable by the ink used with the system to eliminate nucleation sites in the surfaces forming the walls of the chamber and thereby inhibit formation of bubbles from dissolved air contained in ink within the chamber when the ink is subjected to reduced pressure during operation of the ink jet system.

I claim: 
     
       1. A pressure chamber for an ink jet system comprising a chamber formed by a plurality of wall segments, a supply of ink in the chamber having a selected surface energy, first aperture means extending through a wall segment and communicating with an ink jet orifice, second aperture means extending through a wall segment and communicating with an ink supply duct, and a layer of xylylene polymer coating material forming a smooth, continuous, impermeable coating conforming to the configuration of the wall segments of the chamber, the coating being mechanically wettable by the ink, thereby eliminating nucleation sites for bubble formation when ink containing dissolved air within the chamber is subjected to a reduced pressure. 
     
     
       2. A pressure chamber according to claim 1 wherein the coating on the wall segments is between about 0.1 and about 5 microns thick. 
     
     
       3. A pressure chamber according to claim 2 wherein the coating on the wall segments is between about 0.2 and about 2 microns thick. 
     
     
       4. A pressure chamber according to claim 1 wherein the coating comprises a polymer material. 
     
     
       5. A pressure chamber according to claim 1 wherein the coating comprises a material having a surface energy of at least about 33 dynes per cm. and the surface energy of the ink is less than about 33 dynes per cm. 
     
     
       6. A pressure chamber according to claim 1 wherein the coating comprises poly(p-xylylene). 
     
     
       7. A pressure chamber according to claim 1 wherein the coating comprises poly(chloro-p-xylylene). 
     
     
       8. A method for preparing a pressure chamber for an ink jet system for use with ink having a selected surface energy comprising forming a chamber having a plurality of wall surfaces and having a first aperture for communication with an ink jet orifice and a second aperture for communication with an ink supply duct, and introducing a xylylene coating material into the chamber so as to deposit a smooth, continuous coating of the material conforming to the wall surfaces of the chamber, the coating being mechanically wettable by the ink used with the system. 
     
     
       9. A method according to claim 8 including the step of vaporizing a xylylene material and introducing the xylylene vapor into the pressure chamber and depositing a coating comprising xylylene polymer material on the wall surfaces of the pressure chamber. 
     
     
       10. A method according to claim 9 wherein the coating deposited on the chamber wall surfaces comprises poly(chloro-p-xylylene). 
     
     
       11. A method according to claim 9 wherein the coating deposited on the chamber wall surfaces comprises poly(p-xylylene). 
     
     
       12. A method according to claim 8 wherein the coating has a surface energy of at least about 33 dynes per cm. and the ink to be used with the system has a surface energy of less than about 33 dynes per cm.